1. Field of the Invention
The present invention relates to an electricity storage control device for a hybrid vehicle, which can perform travel with the use of only a motor by an electric power of a battery.
2. Description of the Related Art
There are related-art hybrid vehicles that travel while keeping a constant SOC (the amount of storage) of an on-vehicle battery under control. Under the control, the related-art hybrid vehicles travel in an EV mode (EV travel) using only the motor as a power source with an electric power stored in a battery, or achieve a travel distance in the EV travel with the battery nearly fully charged by an external power supply as in a plug-in system.
In the above EV travel of the hybrid vehicle, because the hybrid vehicles travel with only the motor (no engine operates), an operation sound is small, and a person is free from noise. For that reason, the EV travel is significantly effective when the vehicle travels in a residential area or around town in the middle of the night.
Under the circumstances, related-art hybrid vehicle having an EV switch in which when a vehicle occupant operates the EV switch to select the EV travel, only the EV travel is conducted have come on the market.
However, in the EV travel of the related-art hybrid vehicle, because an electric power of the battery is used up to a lower limit constant SOC under control, an electric energy remaining in the battery during or after travel are diverse. In a situation where the vehicle occupant desires the EV travel, for example, when the vehicle enters a residential area close to home, which is a destination, in the middle of the night, or when the vehicle put into a garage the previous day leaves the residential area early in the morning, the battery does not frequently ensure sufficient SOC for allowing the vehicle to travel in the residential area. For that reason, there are many cases in which the EV travel cannot be conducted when it is desired that the vehicle travels silently.
In particular, in the related-art hybrid vehicle, since the SOC of the battery is merely indicated by an indicator as the remaining electric energy (the amount of storage) of the battery, the vehicle occupant cannot understand from the indication by the indicator how long the hybrid vehicle can really conduct the EV travel, and cannot frequently keep the EV travel on the way even if the EV travel of the hybrid vehicle is executed, which makes it difficult to continue silent travel intended by the vehicle occupant.
In the related-art hybrid vehicle, as disclosed in JP-A-2009-248822, in order to get a distance of the EV travel executed with the help of the battery, the amount of charge in the battery is increased according to a target travel distance.
However, JP-A-2009-248822 fails to teach that a desired travel distance of the EV travel is ensured with the electric power remaining in the battery. For that reason, the hybrid vehicle cannot sufficiently utilize the EV travel.